Perplexing J-45 buzz/rattle

[QRST4]

Hello all. Thank you for reading my first post on the forum.

I joined specifically hoping to zero in on a fix for a perplexing buzz/rattle I hear from my '20 J-45. It's not normal fret buzz. The action at the 12th fret is 6/64" bass side, 4/64" treble side. Pretty typical. The action at the nut is OK--when I fret at the 3rd fret, there's enough clearance that I hear a little "plink" when I tap the string down over the 1st fret.

The noise comes from the area of the bridge, but I haven't pinpointed its exact location. It appears under specific conditions:

1. While I am playing "rest strokes" (in my playing, this is normally the bass notes of a bluegrass style "boom-chick" rhythm)
2. with a flatpick (higher dynamics than finger style)
3. in the low register of the instrument (it is most pronounced on the 5th string C3, but can be heard on the 4th and 6th strings at various fret positions to a lesser extent)

I haven't encountered this specific issue on any other guitar I've played--even guitars that cost 10% of what I paid for my J-45. I don't think my playing is not at fault--my touch is on the lighter end of the spectrum. Nonetheless, it seems the problem has something to do with the energy going into instrument during a rest stroke. Perhaps frequency plays a part, too?

The guitar has been inspected at three different shops in my area, including one which has a sterling reputation (the 12th Fret in Portland, OR, where it was set up after I bought it). The feedback I've received has ranged from "I don't hear anything" to "I hear the problem but I can't figure it out".

I've had some fairly typical post-market work done to the instrument: the installation of a bone nut and saddle, and an LR Baggs Anthem. To the best of my recollection, I first noticed the noise after the Anthem was installed. At first, I thought that was the problem, and after a lot of back and forth between Sweetwater, Caleb at Baggs, and the shop that did the installation, I returned the original Anthem and got a replacement from Sweetwater. The issue persisted after the replacement was installed. It's not the pickup.

I read on multiple forum threads that the endpin jack can be problematic, so I fooled around with that a bit (even though the noise is clearly not coming from that area of the guitar). It's not the endpin jack.  Ditto tuning machines.

I've also tried putting the original saddle back in, installing different bridge pins, inspecting the pickup wires and mic module (inside the guitar), installing a variety of different strings. I gave the neck just smidgen more relief (it's probably at about .014). No dice.

I gave up in frustration and for months, I dealt with it as best as I could. Grin and bear it, ya know? I'll sometimes go weeks playing exclusively finger style, under which condition the noise isn't as prevalent (but never completely a non-issue). I periodically try to troubleshoot it by producing the rattle and holding my head close to the guitar to try pinpointing it, and having my wife touch/damp various guitar/pickup parts to see if it disappears. Without exception, this ends in frustration.

Yesterday I revisited it again. I produced and isolated the noise by playing rest strokes at C3 , and for no real good reason, I tried something I hadn't thought of before: mashing down on the string very hard with my fretting finger. The noise disappeared!

Adapting my playing to work around the noise, in light of this discovery, is out of the question for three reasons:

1. mashing the string down that hard defies principles of good fretting technique,
2. and besides, the pressure required to make the rattle disappear causes the pitch to go significantly sharp
3. furthermore, I paid what I view as a lot of money for a fine acoustic instrument--I want my money's worth

Nonetheless, this is the first break I've had in understanding the problem. My first idea--not sure why--was to check the frets with my handy Stew-Mac fret rocker. They look pretty darn level until up around where it doesn't matter. So I've made some progress, but again, I'm stumped.

Y'all have any fresh ideas?

Thanks for your consideration.

[Dave F]

repost this in the acoustic lounge, you'll get more response.

[QRST4]

1 minute ago, Dave F said:

repost this in the acoustic lounge, you'll get more response.

Thanks for the tip, I'll do that now.